Hydraulic power unit control system



2,952,245 7 HYDRAULIC POWER UNITCONTROL SYSTEM John Curlett, Los Gates,and Raymond A. Gurries, San

Jose, Calif., assignors to .Gurries Manufacturing (30., San Jose,Calif., a corporation of California Filed July 13, 1959, sr. Nb. 826,681Claims. (31. 121-41 This invention relates to a hydraulic" systefn forcontrolling the level of a bulldozer or grader blade or the like tocompensate for variations in the level or contour of the ground beingtraversed by. the implement; the system of the present inventionparticularly representing improvements over the system shown in ourPatent No. 2,778,130, dated January 22,1957. i

The major object of this invention, and the main difference in theimproved system over the previous one above identified, is theemployment and incorporation into the system of a servo power boostedunit which gives unlimited power to the pendulum input andeliminates theproblems arising from excessive friction. The new system and mechanism--a1s'o .allows'the use of a standard type of full-flow high'pressurecontrol valve for the power unit instead of a pilot operated valve whichis not smooth acting. 1 r y The system includes a low pressure sensitivependulum operated valve for controlling the operation of the servo unit,and a high pressure valv'efor controllingthe op-f eration of theheavy-duty power unit, and another object of this invention is to'providea hydraulic system so arranged that with the use of a singlepump, both high and low pressure valves will besupplied'with the rfequisite and uniform pressures at all 'As a result, jerkiness inoperation'of the valve controlled units, as would be the case if thepressuresfluctuated, is eliminated, and a smooth operation and.accurate' control is-assui'ed.

The system includes manually controlled 'rneans to operate the highpressure valve independently of the actuation thereof by the servo unit,and a further ob ject of this invention is to improve and simplify theconnecting mechanism between the poweror pendulum operated means and themanually controlled. means over what was employed in the previous aboveidentified system. I 1 I g It is also an object of the invention toprovide a practical, reliable, and durable hydraulic power unit controlsystem, and one which will. be. exceedingly eliective for the purposefor which 'it'is' designed."

These objects are -accomplish'ed, .fby-gmeans of such structure andrelative arrangement ofparts aswill fully appear by a, perusal ofthefollowingjspecification and In the drawings:'

Fig. l is a diagram of"the,"improved system.

Fig. 2 is a fragmentary'side elevationot the preferred form of themanual 'cohtrol;n'1chanisrri.'of the'sy tem.

Referring now more particularly tothe drawings, and to the characters ofreference marked thereon, the system includes a pendulum .1 mounted onthe tractor on which the bulldozer blade or other member is mountedwhose level is to be maintained constant, and which is controlled by ahydraulic ram 2 also mounted on the tractor.

The pendulum is connected by linkage 3 to the plunger 4 of a piston-typevalve 5 of conventionalform. Oombined feed and return conduits 6 leadfrom thistvalve fl to a servo unit which'comp'rises a hydraulicrotary.actu'-. ator of conventional or standard form, and indicated gen,

erally at 7. The feed conduit 8 to valve 5 is' connected" to a source ofpressure, as will be seen later. pendulum, valve, and actuator assemblyis preferably' the same as that shown and described in the copendingapplication of John Curlett, Serial No. 818,923, filed June The rotatingmember 9 of the actuator 7 is fitted with, a spur gear 10 which mesheswith a pinionI11fixedon one shaft 12 of a standard'ior conventional formof 14 of the differential a cam 15 engaged .by

diiferential 13. The other shaft 13.is fitted onits outer end with aroller 16 on one end ofa lever diate its ends in a fixed position.

17 pivoted interme- 20. Combined'feed and return conduits 21 lead tolandfrom the valve to the ends of the High pressure is fed to valve 2'0cylinder of ram2, 'jj through a .ma c n-j duit 22 leading from a supplytank 23 to said valve'.

A pump 24 is interposed in said conduit 22,.and acheck valve C isinterposed in the main conduit 'betweenthe pump and valve 20, and openstoward the latter.; A; secondary conduit 22a connects the tank 23 andconduit 22 at a point in the latter between the pump and checl;

under all conditions of operation.

valve; an unloading valve 25 being interposed in "said secondaryconduit; This unloading valve is preferably the same as that shown inUnited States Patent No. 2,779,346, dated January 29, 1957. v,

An accumulator 26 is also included in therconduit system 22, beingdisposed between the unloading valve 25 and thevalve 20. The returnconduit 27 leads back from valve 20 to the tank 23, while another.conduit 28 drains back to said tank from the housing (notshown), inwhich the valve 5 and actuator 7 are mounted, as shown in the previouslymentioned copending application. a 1 The, feed conduit 8 leading tovalve 5. is connected to the conduit system 22 atia ing valve 25 and theaccumulator 26, and a pressure reducing valve 29 is interposed in saidconduit 8. accumulator 30 is connected to conduits between the reducingvalve 29 and the valve 5. V j

By reason of-the above arrangement, the one pump supplies both thehighand low pressure for the operation of the two halves 5 and 20, andbecause of theinter: position of the accumulators in the relatedconduits, the twoseparatepressures retain their proper proportions Themechanical features of the'improved systemabove described include a handcontrol means foroperating the valve 20 irrespective ofthe pendulumcontrol thereof, just as in the structure shown in Patent No." 2,778,130, noted in the preamble of this specification. j f

.In the present system, .such hand control incans 111- prises a handlever 31'connected to a bevel geari 32 to oscillate the same; said gearmeshing with a pinion 33, This pinion ismounted on a shaft 34onwhichanirre: versible worm 35 is fixedjthe ,worm engaging .a worm h e36 ur d ,0 h i odylq c rrier. ;Qf; flifl ren: t'ial'38. Oneshaft 39 bethis differential has a spur gear 40 fixed thereon which meshes'with aspur pinion 41 fixed on the body or carrier 42 of the differential 13.

A follow-up rod or link 43 connects the moving piston 2a of ram 2 with aradial arm 44- on the other shaft 45 of differential 38; this follow-upunit functioning to the same end as the corresponding device in saidPatent No. 2,778,130.

In operation, it will be seen that by reason of the dual Patented Sept,13, 19 0 p The other "end of the lever is connected by a link 18 topoint between the unload- 3 interconnected differential arrangementemployed, the following action is obtained:

When the rotary member 9 of the servo unit or bydraulic actuator 7 isturned by pendulum actuation of valve 5,.the'pinion 11 connected to theshaft 12 of clifferentia'l 13 is likewise turned; At this time, both theshaft 39 and the carrier 37 of differential 38 are prevented fromrotating because of the then stationary link 43 and the irreversiblemanually controlled worm 35. The carrier 42 of differential 13 is thuslikewise held against rotation because of the interconnected meshinggears 40 and 41. As a result, such rotation of the shaft impartsrotation to shaft 14. This turns the cam 15 to swing lever 17 and thusopens the normally closed valve 20 so as to admit fluid to one end orthe other of ram 2.

If a manually controlled actuation of valve 20 is de sired, suchactuation is effected as follows:

Rotation of worm 35, by reason of its connection with the hand lever,rotates the carrier 37 of differential 38. Since the shaft of suchdifferential is at that time held against movement by link 43, shaft 39will be turned, and by reason of the interconnected gears 40 and 41 thecarrier 42 of differential 13 will be turned. The shaft 12 of (saiddifferential 13 cannot then turn, however, because of its gearedconnection with the stationary and inactive member 9 of the actuator 7.1 As a result, turning of carrier 42 effects the turning of shaft 14 ofsaid differential 13 with the accompanying opening of valve 20, aspreviously described.

In either case, movement of the follow-up link 43 which accompanies themovement of the ram piston 2a, acts to then close valve 20 in thefollowing manner:

Shaft 45 of differential 38 is turned by the pull or push of link 43 onthe radial arm 44 as the ram piston 2a moves. Since carrier 37 of saiddiiferential 38 and shaft 12 of differential 13 cannot then turn, shaft39 of differential 38 and the gear 40 on said shaft are turned. This inturn imparts rotation to gear 41 and carrier 42 of differential 13, thuscausing shaft 14 of differential 13 with the cam 15 thereon-to be turnedin the direction opposite that originally imparted thereto, to effectclosing of valve 20. The use of a double set of differentials in thecontrol mechanism of the control system thus maintains desiredrelationships in the system, which are: (1) the hand control setting;(2) the bulldozer or similar blade motion and position; (3) the pendulumposition; and (4) the operating valve position. a a From the foregoingdescription it will be readily seen that there has been produced such asystem as will substantially fulfill the objects of the invention, asset forth herein.

, While this specification sets forth the present and preferredconstruction of such system, still in practice such deviations therefrommay be resorted to as do not form adeparture from the spirit of theinvention, as defined by the appended claims.

' Having thus described the invention, the following is claimed as newand useful, and upon which Letters Patent are desired:

1. In a hydraulic system, a pendulum, a normally closed valve mountedadjacent the pendulum and having a fluid pressure conduit connectedthereto, means between the pendulum and valve to open the latter uponrelative swinging of the pendulum from a normal position, a hydraulicrotary actuator including a rotary member, a

conduit connected to the valve and actuator to impart rotation to saidmember upon opening of the valve with a resultant flow of fluid throughsaid conduit, another normally closed valve, and a mechanism connectingthe member and said other valve to open the latter upon rotation of themember; said mechanism comprising a gear fixed on and concentric withsaid member, another gear meshing with the first named gear, a shaftunit on which said other gear is fixed, and connection means between theshaft unitand said other valve to actuate the latter upon rotation ofthe shaft unit.

2. In a hydraulic power-unit control system, a differential structurewhich includes alined gear-connected shafts and a gear carrier, apendulum controlled means to rotate one of the shafts, a hydraulic valveto control the operation of the power unit of the system, means betweenthe Valve and the other shaft of the differential structure toactuatethe valve upon suchrotation of the one shaft and the accompanyingfunctioning of the differential structure and rotation of the othershaft thereof, and manually controlled means to actuate saiddifferential structure to cause rotation of said other shaftirrespective of the rotation ofthe one shaft of said structure by thependulum controlled means.

3. A system, as 'nclaim 2, in which said manually controlled meansincludes gear connections to rotate the carrier of the differentialstructure.

4. In a hydraulic power-unit control system, a differential structurewhich includes alined gear-connected shafts and a gear carrier, apendulum controlled means to rotate one of the shafts, a hydraulic valveto control the operation of the power unit of the system, means betweenthe valve and the other shaft of the differential structure to actuatethe valve upon such rotation. of the one shaft and the accompanyingfunctioning of the differential structure and rotation of the othershaft thereof, and manually controlled means to actuate saiddiiferential structure to cause rotation of said other shaftirrespective of the rotation of the one shaft of said structure by thependulum controlled means; said manually controlled means comprisinganother, difierential structure which includes alined gear-connectedshafts and a gear carrier, manually operated means to rotate the lastnamed carrier, a gear connection between one shaft of said otherdifferential structure and the carrier of the first named differentialstructure, the power unit of the system including a movable member movedupon opening of said valve, and a follow-up connection between themovable member and the other shaft of said other differential structureto rotate such other shaft upon movement of said movable member. V

5, A system, asf in' claim 4, in which said manually operated meanscomprises a worm gear fixed on said last named carrier, andanirreversible manually rotated worm engaging the worm gear. 1

References lited in the file of this patent UNITED STATES PATENTS588,946

Bergman Aug. 31, 1897 2,275,963 Herman et a1. Mar. 10, 1942 2,367,115Goepfrich Jan. 9, 1945 2,623,358 Greer Dec. 30, 1952 2,778,130 Gurrieset a1. Jan. 22, 1957 2,892,310 Mercier June 30, 1959 2,902,979 Gurrieset al.. Sept. 8, 1959

